Individually Owned: 150,657
Corporate Owned: 137,281
N/A Airport
Aircraft Accident/Incident Report
Chualar, California 93925
Sunday, August 4, 2013 10:30 PDT
NTSB Narrative Summary Released at Completion of Accident
The pilot stated that he was operating the helicopter at a low altitude when he heard a loud boom and then noted a decrease in main rotor rpm. During the ensuing emergency landing, the helicopter impacted the ground, the tail boom separated from the fuselage, and the helicopter rolled onto its right side. Postaccident examination revealed that the main driveshaft had disconnected and that the bolts attaching the forward coupling to the transmission had failed. Portions of two of the four bolts that attached the forward coupling to the transmission were found, and the fractured threaded remnants (with nuts attached) were examined. One of the remnants was fractured through its entire cross-section due to fatigue, and the other remnant fractured through about 75% of its cross-section due to fatigue; the remainder of the failure on this remnant occurred in overload. Both fracture faces had multiple fatigue origins around about 1/4 of their circumferences, indicating relatively high stresses. No mechanical damage was noted at the fatigue origin locations. One of the remnants displayed smearing of adjacent threads and decreased height of the nut, suggesting this bolt had a relatively large amount of play. It is likely that the large amount of play was due to improper torqueing of the bolts when the driveshaft was reinstalled after extensive maintenance that was performed on the helicopter about 3 months and 197 flight hours before the accident.
NTSB Probable Cause Narrative
Maintenance personnel's failure to properly tighten the bolts securing the main driveshaft to the transmission, which resulted in fatigue failure of the bolts and disconnection of the driveshaft during low-altitude flight.
Event Information
| Type of Event | Accident |
| Event Date | 8/4/2013 |
| Event Day of the Week | Sunday |
| Time of Event | 1030 |
| Event Time Zone | Pacific Daylight Time |
| Event City | Chualar |
| Event State | CALIFORNIA |
| Event Country | -- |
| Zipcode of the event site | 93925 |
| Event Date Year | 2013 |
| Event Date Month | 8 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 363215N |
| Event Location Longitude | 1213230W |
| Event Location Airport | N/A |
| Event Location Nearest Airport ID | -- |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 953 Pacific Daylight Time |
| Direction of event from weather observation facility (degrees) | 335 |
| Weather Observation Facility ID | SNS |
| Elevation of weather observation facility | 85 |
| Distance of event from weather observation facility (units?) | 8 |
| Time Zone of the weather observation | PDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 600 |
| Lowest Non-Ceiling Height | 600 |
| Sky/Lowest/Cloud Conditions | Thin Broken |
| Sky Condition for Lowest Ceiling | Broken |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 10 |
| Air Temperature at event time (in degrees celsius) | 13 |
| Dew Point at event time (in degress fahrenheit) | 11 |
| Wind Direction (degrees magnetic) | -- |
| Variable Wind Indicator | Variable |
| Wind Speed (knots) | -- |
| Wind Velocity Indicator | Light and Variable |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 30.04 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | Minor |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | 1 |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | 1 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 32199 |
| NTSB Notification Source | ROC |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Nov 21 2013 9:01PM |
| User who most recently changed record | strj |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N90146 |
| NTSB Number | WPR13LA358 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 137: Agricultural |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | BELL |
| Aircraft Model | 206B |
| Aircraft Series Identifier | III |
| Aircraft Serial Number | 1614 |
| Certified Max Gross Weight | 3350 |
| Aircraft Category | Helicopter |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 2 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | 100 Hour |
| Date of Last Inspection | Jul 10 2013 12:00AM |
| Airframe hours since last inspection | -- |
| Airframe Hours | 18985 |
| ELT Installed | No |
| ELT Activated | Unknown |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | R AND B HELICOPTERS INC |
| Aircraft Owner Street Address | PO BOX 4087 |
| Aircraft Owner City | SALINAS |
| Aircraft Owner State | CA |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 93912-4087 |
| Operator is an individual? | No |
| Operator Name | R AND B HELICOPTERS INC |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | PO BOX 4087 |
| Operator City | SALINAS |
| Operator State | CA |
| Operator Country | USA |
| Operator Zip code | 93912-4087 |
| Operator Code | -- |
| Owner has at least one certificate | Yes - certificate holder |
| Other Operator of large aircraft? | -- |
| Certified for Part 133 or 137 Operation | -- |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | -- |
| Indicates Domestic or International Flight | -- |
| Operator carrying Pax/Cargo/Mail | -- |
| Type of Flying (Per_Bus / Primary) | Aerial Application |
| Second Pilot on Board | No |
| Departure Point Same as Event | Yes |
| Departure Airport Code | -- |
| Departure City | Chualar |
| Departure State | CA |
| Departure Country | USA |
| Departure Time | 1020 |
| Departure Time Zone | PDT |
| Destination Same as Local Flt | dest & departure same, accident can occur anywhere |
| Destination Airport Code | -- |
| Destination City | Chualar |
| Destination State | CA |
| Destination Country | USA |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Nov 21 2013 9:03PM |
| User who most recently changed record | strj |
| Since inspection or accident | Last Inspection |
| Event Location Runway Number and Location | N/A |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |